1. Technical Field
The present disclosure relates to an image sensor for imaging an object and an imaging device equipped with the image sensor.
2. Description of the Related Art
An image sensor has a photoelectric conversion element which converts an object image (light) to an analog electric signal, and an analog-to-digital (AD) converter which converts the analog electric signal to a digital signal. The image quality of an image captured by the image sensor depends largely on the performances of the AD converter. Accordingly, the AD converter mounted in the image sensor is required to have a high accuracy so that even weak light can be detected with high sensitivity.
International Publication No. WO2014/141350 discloses an AD converter configured by combining a delta-sigma converter which produces an upper-bit digital signal and a recursive AD converter which produces a lower-bit digital signal to perform in total a highly accurate analog-to-digital conversion.